Abstract

An experiment is proposed to test the theory recently advanced by Feynman and Gell-Mann on the vector interaction in β decay. According to the theory, the Fermi coupling constant is not appreciably altered by renormalization, in agreement with experiment. A further property of the theory is exploited here, that analogous γ and β transitions in light nuclei have proportional matrix elements, as far as the V interaction is concerned. In particular, the V interaction gives rise to "weak magnetism" analogous to the magnetic effects that induce the emission of M1 photons. This "weak magnetism" obeys Gamow-Teller selection rules and interferes with the A coupling, distorting the spectra of high-energy β transitions with ΔJ=1 (no).
It is suggested that the β spectra of B12 and N12 be measured accurately and compared. Departure from linearity of the Kurie plot should be noticed in each case; the ratio of the spectra can be calculated with confidence on the basis of the theory, which predicts a 20% effect. The measured γ-ray width of the 15.11-Mev state in C12 is used in the calculation.